Issues with combining call streams in Call Manager

[Don Schlising]

We recently ran into an issue where we had two internal callers having a conversation, and within 30 seconds of the call, they could hear another separate conversation from another call.  The stream that joined their call must have only been a one way stream as they could hear the other conversation, but the second party could not hear anyone on the original call.

This is the first time we have run into this issue, and I expect that it may have something to do with our new call recording solution, remote span port configuration or IOS version issue.  (The solution is using a remote span port to provide passive recording.)  We have a few 3560G switches that are reporting to one remote span port for the IP phone recording.  Is it possible that RTP streams were combined?  I spent some time researching the issue online and wasn't able to find anyone that had a similar problem.

The call manager server is 7.1.3.20000-2, the router is a 2821 running 12.4(20)T6 and the switches are 3650Gs (I don't have the IOS version but can get it if needed). 

We can call TAC as needed, but I thought that I would drop a quick note here to see if anyone else has run into a similar issue.

Thank you,
Don

[Pratik Jhaveri]

Don,

It is indeed an odd behavior. However IP phones will not switch over the RTP connection until and unless they have been instructed by the CUCM.

This issue would certainly require further analysis of the CUCM trace. But in the mean time the best way to is browse through the IP phone's web page and check the "Remote IP address". If the Remote IP address is not of Party B, then we can suspect CUCM is doing something which is causing this behavior or else it could be the network or 3rd party device.

Thanks

Pratik

[asandborgh]

Don,

Was either caller calling in  from the PSTN?

The reason I ask is this - to Pratik's point the RTP streams (two) are unidirectional between the two endpoints.  In theory,  for another stream third party stream to be added there would need to be a conference bridge invoked (even if they were only hearing the one-sided conversation), because there would be three IP addresses in the conversation.  I have actually had this occurence happen over the PSTN to me before - rarely, but have had it occur...

HTH,

Art